help! sick fish

[zigg]

i turned the lights on and noticed the lack of color and watched for about 20 minutes. ive seen them plenty of times resting and this was different. ive never seen one of my tiger barbs run into the glass and keep trying to push on it. to me that says the water conditions are bad but i tested it before i left for work last night and everything was fine. is it possible that there color loss could be from the stress of the small tank?the rainbows and bichir were never really active mostly just hung around till food came and seem fine in the tank. no fish in there is bigger than 1 3/4 inches